From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Table of specifications for armature windings for various dynamos.
| Identifier | ExFiles\Box 68\4\ scan0196 | |
| Date | 29th September 1919 | |
| X 1640 29.9.19. TABLE OF ARMATURE WINDINGS (DYNAMOS) Machine | C.A.V.N.C.R.R. | Lucas E.575. | Smith(T & M) A.{Mr Adams} | Bijur. | Liberty. | R.R.20 HP. | Lucas A.400. | Smith T & M 24. Number of poles (even) (p). | 2 | 2 | 2 | 4 | 4 | 4 | 4 | 2 Number of slots (s) | 24 | 30 | 19 | 15 | 21 | 17 | 43 | 19 Type of winding. | Progressive lap. | | Retrogressive lap. | | | Retrogressive Wave. | | Retrogressive lap Number of conductors (n') | 672 | | 760 | | | 408 | | 760 Conductors per slot (n'/s) | 28 | | 40 | | | 24 | | 40 Coils per slot (c/s) | 2 | 1 | 2 | 3 | 1 | 3 | | 2 Number of coils or com. bars (c) | 48 | 30 | 38 | 45 | 21 | 51 | 43 | 38 Turns per coil (n'/2c) | 7 | | 10 | | | 4 | | 10 Virtual conductors (2s) | 96 | | 76 | | | 102 | | 76 Winding pitch in virtual conductors (z) | 49 forward 47 backward | | 33 forward 35 backward | | | 25 R | | 33 for'd 35 back'd Step Winding pitch in slots. | 12 | | 8 | | | 12 | | 8 | ||